Rotary machine with rotor axial positioning means

ABSTRACT

A rotary motor of the sliding vane type is shown. The rotor has two stub shafts rotatably supported in the housing by means of ball bearings. A pile of Belleville springs are braced between a shoulder on one of the stub shafts and its associated bearing so as to bias the rotor into an axial position defined by a counterbalancing ring that is adjustably attached to the other stub shaft by means of a set screw.

United States Patent 1191 Hansson Apr. 16, 1974 1 ROTARY MACHINE WITHROTOR AXIAL 3,719,440 3/1973 Snider 418/270 POSITIONING MEANS 1,994,7863/1935 Redfield 418/134 1,730,145 10/1929 Hildreth 418/133 [75]Inventor: Gunnar Chrlster Hansson, 2,762,340 9/1956 Roggenburk......418/134 Stockholm, Sweden 3,309,965 3/1967 Weickgenannt 418/133 [73]Assignee: Atlas COPCO Aktiebolag, Nacka, FOREIGN PATENTS OR APPLICATIONSSweden 1,308,375 9/1962 France 418/135 [22] Filed: Oct. 6, 1972 [21] ApNo; 295,703 Primary Examiner-Carlton R. Croyle Assistant Examiner-JohnJ. Vrablik At ,A t, F -F] &F'h f [30] Foreign Application Priority Datatomey gen or lrm ynn us an Jan. 14, 1971 Sweden 13002/71 [57] ABSTRACT 207 418 ,4 8 270, [5 1 U 8 Cl 418/l ga i /259 A rotary motor of theslldmg vane type 1s shown. The [51] Int Cl F01 c 21/00 F16: 13/00 F64:15/00 rotor has two stub shafts rotatably supported in the [58] Fie'ld418/131 134 135 housing by means of ball bearings. A pile of Belleville418/107 30/189A springs are braced between a shonider on one of the403/259 6 stub shafts and its associated bearing so as to bias the rotorinto an axial position defined by a counterbal- [56] References Citedancing ring that is adjustably attached to the other f UNITED STATESPATENTS stub sha t by means of a set screw 3,429,228 2/1969 Stoica418/107 14 Claims, 4 Drawing Figures RATENTEDAPR 16 I974 SHEET 1 (IFROTARY MACHINE WITH ROTOR AXIAL POSITIONING MEANS This invention relatesto a rotary machine particularly but not exclusively of the typeprovided with vanes, for instance a vane motor, a vane pump or a vanecompressor with a housing and a rotor which has two opposite stub shaftsjournalled by roller or ball bearings in the housing, the outer races ofthe roller or ball bearings being axially supported in the housing andthe rotor being axially sealed to the housingby narrow clearances.

In such machines the rotor can either be axially fixed in a positionbetween its axial end positions or be axially freely movable between theend positions. In an air pressure driven vane motor the distance betweenthe end positions, i.e., the total axial clearance, is for instance 0.06mm. An axially fixed rotor is preferable considering the wear.Furthermore, if the rotor can be fixed in a position which gives aboutthe same clearance on both sides, a considerably reduced leakage isobtained.

The object of the invention is therefore to provide for the fixation ofthe rotor in an axial middle position in a way that is technically andeconomically favourable and does not require extreme tolerances of thedimensions of the fixation details. According to the present inventionthere is provided a rotary machine comprising a housing, a rotor withtwo opposite stub shafts each being journalled in the housing by meansof a bearing with an outer race and an inner race and rolling elements,the outer races of the bearings being axially supported in the housingand the rotor having narrow axial clearances to the housing, a springbraced between a shoulder on one of the stub shafts and the inner raceof one of the bearings so as to apply an axial load to the rotor and anelement axially adjustably attached to the other of the stub shafts andabutting against the inner race of the other bearing so as to take upand transmit to this inner race the axial load applied to the rotor bythe spring whereby to hold the rotor in an axially fixed position.

The invention will be further described with reference to theaccompanying drawings in which: FIG. 1 is a longitudinal section alongline 1-1 in FIG. 2 through an air pressure driven vane motor inaccordance with the invention, FIG. 2 is a cross section along line 2--2in FIG. 1, FIG. 3 is a longitudinal section through a detail shown inview in FIG. 1, and FIG. 4 is a longitudinal section similar to FIG. 1through a modified embodiment.

The vane motor shown in the FIGS. 1-3 has a housing with a cylindricalpart 11 and two end plates 12,13 screwed together in order to define acylinder chamber. Instead of being directly screwed together the parts 11,12,13 can be clamped together by means of an outer housing notillustrated. A rotor 16 has two stub shafts 17,18 and a number ofgrooves 19 for vanes 20. A ball bearing, comprising an outer race 22, aninner race 23 and balls 21, is moved onto the shaft 17 so that the outerrace is radially as well as axially supported in the end plate 12. Inthe same way, a ball'bearing for the stub shaft 18 is mounted in the endplate 13. This bearing comprises an outer race 25, an inner race 26 andballs 24. The shaft 17 is provided with a groove in which a split snapring 27 is mounted. Two Belleville springs 28,29 are braced between thesnap ring 27 and the inner race 23 of the bearing 21,22,23. Thus, the

balls 21 of the bearing will transmit the force of the springs from theinner race 23 to the outer race 22. The latter is axially supported inthe end plate 12 and thus, the springs bias the rotor 16 towards the endplate 12, i.e., to the left in FIG. 1. A ring or washer 30 is axiallysupported by the inner race 26 of the other bearing 24,25,26 and bymeans of a set screw 31, the rotor 16 can be pulled against the endplate 13, i.e. to the right in FIG. 1, against the action of the springs28,29. In FIG. 3, the stub shaft 18 and the washer 30 are shown insection.

When the vane motor is to be assembled, the washer 30 and the set screw31 will be mounted as the last part. Suitably, the set screw 31 is firstgiven a coat of a glue or of any other hardening fluid or substance, forinstance an anaerob plastic, and the set screw is screwed to theposition in which the rotor 16 easily can be rotated manually, i.e.,until the axial force between the rotor 16 and the end plate 12 of thehousing starts decreasing but the rotor still abuts the end plate. Theangular position of the set screw 31 is now indicated and the screw isturned until it begins to be difficult to rotate the rotor manuallyagain, i.e., until the rotor instead abuts the other end plate 13 of thehousing. The angular position of the set screw 31 is again indicated.The screw is now adjusted into a position right between the indicatedpositions which results in the rotor 16 taking up its middle position inwhich the clearances between the rotor and the end plates 12,13 of thehousing are equal. After some time, the anaerob plastic has hardened andthe set screw 31, as well as the rotor, has been fixed in its positions.Of course, any other suitable locking method can instead be used for thescrew 31.

The Belleville springs 28,29 are for instance selected to give a springforce of about 20 kp for a rotor diameter of 50 mm. Thereby, a veryclose sliding fit can be permitted between the stub shafts 17,18 and theinner races 23,26 of the bearings so that the wear between the stubshafts and the inner races will be almost eliminated. Still, the springs28,29 will be strong enough to axially displace the rotor in the innerraces of the bearings. The fact that the bearings constantly are axiallyloaded by such a great force as, for instance, 20 kp has no negativeinfluence on their durability.

In the modified embodiment shown in FIG. 4 the rotor 16 is clampedbetween the inner sides of the inner races 23,26 of the two bearingsinstead of between the outer sides. The outer races 22,25 of thebearings have such a tight fit (i.e., press fit) that they will remainfixed in the end plates 12,13 of the housing in spite of the fact thatthey are loaded outwards by means of the spring 28,29. A shoulder 27 onthe stub shaft 17 corresponds to the snap ring 27 and the other elmentsof FIG. 4 corresponding to elements in FIGS. 1-3 have also been giventhe same reference numerals as in FIGS. 1-3.

1. A rotary machine comprising:

a housing,

a rotor with two opposite stub shafts each of said stub shafts beingjournalled in the housing by means of a bearing with an outer race, aninner race and rolling elements, the outer races of the bearings beingaxially supported in the housing and the rotor having narrow axialclearances to the housing,

a shoulder on a stub shaft,

a spring braced between the shoulder on one of the stub shafts and theinner race of one of the bearings so as to apply an axial load to therotor, and

an adjusting means axially adjustably attached to the other of the stubshafts and abutting against the inner race of the other bearing so as totake up and transmit to the inner race of said other bearing the axialload applied to the rotor by the spring whereby to hold the rotor in anaxially fixed position which is defined by the position of saidadjusting means on said other stub shaft.

2. A rotary machine as defined in claim 1 in which said shoulder isarranged on the outside of said one bearing and said spring is bracedbetween said shoulder and the outer side of the inner race of thebearing associated therewith, said adjusting means abutting against theouter side of the inner race of the other bearing.

3. A rotary machine as defined in claim 1 in which said shouldercomprises an open snap ring in a groove in a stub shaft.

4. A rotary machine as defined in claim 1 in which said rotor isprovided with a number of substantially radial grooves in which vanesare disposed to seal with their outer protruding edges against acylindrical wall formed in the housing, said cylindrical wall and saidvanes forming expansible chambers.

5. A rotary machine as defined in claim 1 in which said adjusting meanscomprises a threaded member adjustably threaded into said other stubshaft in the axial direction thereof.

6. A rotary machine as defined in claim 1 in which said adjusting meansincludes an element fastened in the end of said other stub shaft bymeans of a set screw.

7. A rotary machine as defined in claim 6 in which said elment comprisesa washer.

8. A rotary machine as defined in claim 6 comprising a binding layer forlocking the threads of said set screw in the stub shaft.

9 A rotary machine as'defined in claim 1 in which said spring comprisesat least one Belleville spring.

10. A rotary machine as defined in claim 9 in which said springcomprises a plurality of cooperating Belleville spring.

11. A rotary machine as defined in claim 1 in which said shoulder isarranged on the inside of said one bearing and said spring is bracedbetween said shoulder and the inner side of the inner race of thebearing associated therewith, said adjusting means abutting against theinner side of the inner race of the other bearing.

12. A rotary machine as defined in claim 11 wherein said outer races ofsaid bearings are press-fit in said housing so as to be retainedtherein.

13. A rotary machine as defined in claim 11 wherein said adjusting meanscomprises a first element axially slideably engaging said other stubshaft and abutting the inner side of the inner race of said otherbearing, and a set screw adjusting the axial position of said firstelement relative to said other stub shaft.

14. A rotary machine as defined in claim 13 wherein said set screwthreadably engages said first element and abuts the end of said otherstub shaft.

UNITED S TATES PATENT OFFICE CERTIFICATE CORRECTION Patent No. 3,804,562 Dated April 16, 1974 Inventbr(s) Gun'riar Christer HANSSON I Itis certified that error appears in the above-identified patent and thatsaid I'ietters Patent are hereby corrected as shown below:

Psge 1, i rz the heading, change priority data to read I as follows z, II

--October 14, 1971 Sweden ..'..13-002/71--;

Column 4; ,ljjn e 12, change "sprihg" to -spr i ngs-.

Signedsnd sealed this 31st day of December 1974.

f EAL) Attest:

I :M'CCCY M; GIBSON JR.

Attesring Officer C. MARSHALL DANN Commissioner of Patents I po'wsouscoMM-oc scan-pew U.$. GOVERNMENT PRINTING OFFICE 7 I!" 0-366-334-

1. A rotary machine comprising: a housing, a rotor with two oppositestub shafts each of said stub shafts being journalled in the housing bymeans of a bearing with an outer race, an inner race and rollingelements, the outer races of the bearings being axially supported in thehousing and the rotor having narrow axial clearances to the housing, ashoulder on a stub shaft, a sprIng braced between the shoulder on one ofthe stub shafts and the inner race of one of the bearings so as to applyan axial load to the rotor, and an adjusting means axially adjustablyattached to the other of the stub shafts and abutting against the innerrace of the other bearing so as to take up and transmit to the innerrace of said other bearing the axial load applied to the rotor by thespring whereby to hold the rotor in an axially fixed position which isdefined by the position of said adjusting means on said other stubshaft.
 2. A rotary machine as defined in claim 1 in which said shoulderis arranged on the outside of said one bearing and said spring is bracedbetween said shoulder and the outer side of the inner race of thebearing associated therewith, said adjusting means abutting against theouter side of the inner race of the other bearing.
 3. A rotary machineas defined in claim 1 in which said shoulder comprises an open snap ringin a groove in a stub shaft.
 4. A rotary machine as defined in claim 1in which said rotor is provided with a number of substantially radialgrooves in which vanes are disposed to seal with their outer protrudingedges against a cylindrical wall formed in the housing, said cylindricalwall and said vanes forming expansible chambers.
 5. A rotary machine asdefined in claim 1 in which said adjusting means comprises a threadedmember adjustably threaded into said other stub shaft in the axialdirection thereof.
 6. A rotary machine as defined in claim 1 in whichsaid adjusting means includes an element fastened in the end of saidother stub shaft by means of a set screw.
 7. A rotary machine as definedin claim 6 in which said elment comprises a washer.
 8. A rotary machineas defined in claim 6 comprising a binding layer for locking the threadsof said set screw in the stub shaft.
 9. A rotary machine as defined inclaim 1 in which said spring comprises at least one Belleville spring.10. A rotary machine as defined in claim 9 in which said springcomprises a plurality of cooperating Belleville springs.
 11. A rotarymachine as defined in claim 1 in which said shoulder is arranged on theinside of said one bearing and said spring is braced between saidshoulder and the inner side of the inner race of the bearing associatedtherewith, said adjusting means abutting against the inner side of theinner race of the other bearing.
 12. A rotary machine as defined inclaim 11 wherein said outer races of said bearings are press-fit in saidhousing so as to be retained therein.
 13. A rotary machine as defined inclaim 11 wherein said adjusting means comprises a first element axiallyslideably engaging said other stub shaft and abutting the inner side ofthe inner race of said other bearing, and a set screw adjusting theaxial position of said first element relative to said other stub shaft.14. A rotary machine as defined in claim 13 wherein said set screwthreadably engages said first element and abuts the end of said otherstub shaft.